Electrical systems with packaged electrical and electronic components are known and are in use. For example, Motor Control Centers (MCC's) are used for power and data distribution in large and industrial operations. In MCC's, a variety of components, such as switchgear, semiconductor power electronic circuits, programmable logic controllers, motor controllers, and so forth, are housed in large electrical enclosures that may be subdivided into sections or columns, which may be further subdivided into compartments. The MCC includes associated bus bars, interconnections and supporting structures for distribution of electrical power to the various compartments.
Typically, the MCC is connected to a main power line that may feed three-phase AC power to horizontal bus bars of the MCC. The horizontal bus bars, in turn, may feed the three-phase power to vertical bus bars disposed in each of the sections or columns of the MCC. The vertical bus bars, in turn, may feed the three-phase power to various electrical units (which typically include electrical components) that are installed in compartments of a section. The electrical units, in turn, may provide power terminals (conductors), such as copper bus bars, for feeding the three-phase power to a system environment, such as motors, as may be required for various applications.
It is often desirable to prevent such electrical units from reaching excessive temperatures as such temperatures for prolonged periods could result unpredictability and/or damage to the system. It is generally known to provide ventilation or airflow in electrical systems as a method for removing heat. Such ventilation can include an opening in the system for air to pass through to remove the heat. However, for MCC's, such openings may expose the system to possible damage from the environment, such as water intrusion, penetration of solid objects such as wires, and the like, and/or could expose the surrounding environment to the possibility of hazards such as arc flash or blast, a type of electrical discharge that could result from a low-impedance connection through air to ground or another voltage phase. Consequently, it is desirable to provide an improved system for ventilation protection which mitigates one or more of the foregoing disadvantages.